Method of treating thermoplastic synthetic filaments



March 23, 1965 METHOD OF TREATING THERMOPLASTIC SYNTHETIC FILAMENTS Filed Sept. 9, 1963 FIG.I

E. G. WHALON ETAL 2 A w r1\ 1' e -j S :dO l- Mafi INVENTORS ERNEST G. WHALON THOMAS REID ANTHONY OSOWSKI 6) gm, aw,

ATTORNEYS 3,175,029 METHOD OF TREATING THERMOPLASTIC SYNTHETIC FILAMENTS Ernest G. Whalon and Thomas Reid, Danielson, and Anthony J. Osowski, Norwich, Conn., assignors to The Hale Manufacturing Company, Putnam, Conn., a corporation of Delaware Filed Sept. 9, 1963, Ser. No. 307,595 5 Claims. (Cl. 264-290) In the manufacture of man-made filaments, particularly those that are melt spun, it is common practice to package the filaments on spools or the like prior to subjecting the filaments to a drawing operation to increase the molecular orientation thereof. Quite often it is found that the substantially unoriented collected filaments are of substandard quality such that the subsequent drawing operation is not economical, when performed in the usual manner. Heretofore, substandard undrawn filaments were salvaged by cutting them in an axial direction with respect to the spool on which they are wound. While this operation permits the spool to be quickly reused, the salvaging of these cut filaments requires the relatively expensive operation of garnetting. Furthermore, the cut filaments should be stretched before they will exhibit acceptable load-bearing ability in yarn spun therefrom; and the cut filaments are of random lengths which sometimes is not desirable.

It is the principal object of the present invention to provide a method of treating packaged substantially unoriented synthetic filament yarn to improve the physical properties thereof.

It is another object of the present invention to provide a method of stretching packaged substantially unoriented thermoplastic filaments normally regarded as substandard quality to improve the quality thereof such that the filaments can be cut into uniform length staple fibers from which excellent quality yarn can be spun.

Other objects will become apparent from the following detailed description.

In general, these objects are accomplished by a novel method of massively stretching packaged substantially unoriented thermoplastic filaments in a particular manner. A source of these filaments is provided by a number of holders of yarn on which filaments are commonly wound subsequent to formation thereof but before being molecularly stretched. A plurality of ends of yarn on these holders are wound together on a spool or like yarn holder to form an accumulated strand having a total denier in the range of about 50,000-1,000,000. A number of these spools on which such accumulated strands are wound are assembled. The continuous strands are led from each of the spools together in spaced relation through the nip of a first pair of very heavy rollers. To this nip a very high pressure is imparted. From the first pair of rollers the continuous strands are led separately through the nip of a second pair of similar heavy rollers. From the second pair of rollers, the continuous strands are lead separately through the nip of a third pair of similar heavy rollers. The third pair of rollers is rotated at a higher speed than the second pair of rollers which, in turn, is rotated at a higher speed than the first pair of rollers to provide two distinct stages of draw. Thereafter, the strands are condensed into a single strand, the filaments of which are molecularly oriented. The single strand then is wound on a spool or the like. For best results all the steps are carried out at a temperature in the range of about 20-35 C. The preferred total draw ratio employed in the process is in the range of about 3.04.0. The draw ratio in the first stage of draw preferably will be about 1.52.0 or higher. The process is most advantageously applicable to treating nylon filaments, particularly of the 66 type.

The invention can be further understood by reference to the accompanying drawing wherein:

FIGURE 1 is a plan view illustrating one arrangement of apparatus suitable for stretching filaments in the twostage operation of the invention; and

FIGURE 2 is a side elevation view of the apparatus shown in FIGURE 1.

Numeral 10 indicates in general a series of spools or cores 12, in this case twelve in number are illustrated. Upon each of these cores is wound a large total denier strand of substantially unstretched (molecularly unoriented) thermoplastic synthetic continuous filaments.

These strands each provide an end 14. Guides or the like 16 above the cores are provided for guiding the strands removed over an end of the cores separately in substantially parallel spaced relation. From the guides the ends are led through a bath 18 containing a liquid beneficiating agent such as a finish, lubricant or the like. This passage of the ends through the bath is not of critical importance to the invention and can be avoided entirely, if desired.

The twelve ends are all spaced apart as shown in FIG- URE l; and they are kept separated while passing through the bath 18 by the use of a conventional guide or the like 20 which can be a series of individual guides holding the separate strands independently of each other.

A first pair of heavy superposed nip-forming pressure rolls is provided for forwarding the strands thereto from the spools. The pair of rolls consists of a lower roll 22 and an upper roll 24. These rolls are extremely heavy and may weigh about 3,000 pounds, for example. Means are provided for driving the first pair of rolls at a first peripheral speed.

It has been found advantageous to provide pressure to the nip of the first pair of rolls in addition to that provided by the weight of the rolls. For example, 5,000 pounds of additional pressure is quite suitably applied to top roll 24. An extremely powerful drag is imparted to the 12 ends in the strand path in stretch area 26 wherein the strands are drawn.

A second pair of heavy superposed nip-forming rolls is provided for forwarding the strands thereto from the first pair of rolls. The pair of rolls consists of a lower roll 28 and an upper roll 30. In this case the rolls are the same as before described, being smooth-surfaced pressure rolls. However, it has been found that there is no significant advantage of applying extra pressure to the upper roll 30. Means are provided for driving the second pair of rolls rat a peripheral speed gre ".ter than the first pair of rolls.

The 12 ends, still separate, then proceed into and tthrough stretch area 32 where the strands are additionally drawn to achieve desired levels of tenacity, elongatibn, etc. A third pair of heavy superposed nip-forming rolls for forwarding the strands thereto from the second pair of rolls is provided. The pair of rolls consists of a lower roll 34 and an upper roll 36. These rolls are extremely heavy, as are the other two pairs. However, as in the case of the first pair of rolls it has been found advantageous to provide considerable additional pressure to the nip :of the third pair of rolls. For example, 5,000 pounds of additional pressure is suitably applied to upper roll 36. Means are provided for driving-the third pair of rolls at a peripheral speed greater than the second pair of rolls. Thus, rolls 34 and 36 are rotated at a predetermined speed faster than the intermediate rolls 28 and 30; and rolls 28 and 30 are rotated at a predetermined speed faster than initial rolls 22 and 24, usual driving means being employed.

The 12 ends converge in the area indicated at 38 to a guide or condenser 40 where the ends are gathered together for the first time into one massive strand 42. This stretched single massive strand is wound on a single core As an example, several ends of nylon-66 filament yarn on a like number of spin bobbins was wound together on a spool to form an accumulated strand of approximately 350,000 total denier. Twelve of these spools containing like accumulated strands were prepared. The 12 ends were drawn as illustrated in the drawing, employing an over-all draw ratio of 3.5. Thus, in area 38 each of the 12 strands had a total denier of about 100,000. The sin gle massive strand at 40 had a total denier of approximately 1,200,000 and was wrapped on the spool at 44. The strand was crimped and cut into staple fibers. Yarn spun from these fibers was woven into excellent fabric.

The method of the present invention is applicable to a wide variety of continuous filament yarn, the requirement being that the yarn is made from a thermoplastic synthetic polymer and can be extended by drawing and then show increased molecular orientation along the filament axis. As examples of synthetic polymers polyethylene, polypropylene, polyurethane, acrylonitrile polymers, polyesters and nylons, particularly nylon-6 and nylon-66, can be named.

While the present method is suitable for treatment of yarn of first quality, it has been found that substandard yarn contained on spin bobbins can be advantageously processed. Ordinarily, such substandard yarn is merely cut from the bobbins by the filament manufacturer; and the cut stock is then sold to garnetters or other processors who cut, garnett, card and crimp it and who subjected the stock to whatever other steps necessary to prepare same for spinning into yarn. Obviously, when waste yarn is processed in the prior art manner, the fibers are of random lengths. The present method described above, however, utilizes the waste material not in the form of cut fibers, but in the form of substantially continuous filaments, at least insofar as each spool 12 is concerned, so that the filaments are drawn when Wound on roll 44.

The process allows one to unwind the massive strand from the core at 44, steam it, crimp it, heat it to make the crimp permanent, and then cut it into tops, the fiber lengths of which are uniform. A very high-grade uniform length staple yarn can be spun from this uniform length fiber material, as distinct from the rand-om length fiber yarn heretofore produced from substandard yarn wound on spin bobbins by filament manufacturers. Numerous other advantages are associated with the present process.

Having thus described our invention and the advantages thereof, we do not wish to be limited to the details herein disclosed, other than as set forth in the claims.

What we claim is:

1. The process of treating thermoplastic synthetic filaments comprising the steps of:

(a) winding a plurality of ends of substantially unoriented filaments on a spool in an accuumulatcd strand having a total denier in the range of about 50,0001,000,000;-

(b) assembling a number of such spools;

(0) leading a continuous strand from each spool simultaneously and separately through the nip of a first pair of heavy rollers;

(d) imparting a pressure to said nip suflicient to provide a drag for a first stage of stretch;

(e) leading the continuous strands separately to the nip of a second pair of similar heavy rollers;

(f) leading the continuous strands separately through the nip of a third pair of similar heavy rollers;

(g) rotating the third pair of rollers at a higher speed then the second pair of rollers to provide a second stage stretch;

(h) rotating the second pair of rollers at a higher speed than the first pair of rollers to provide a first stage stretch;

(i) condensing the strands into a single stretched strand; and

(j) winding the single stretched strand on a spool;

all of the steps being carried out at a temperature in the range of about 20-35 C. and the total draw ratio employed being in the range of about 3.0-4.0.

2. The process of claim 1 wherein the filaments are composed of nylon.

3. The process of claim 2 wherein the nylon is nylon- 66.

4. The process of treating thermoplastic synthetic filaments comprising the steps of:

(a) winding continuous waste filaments on a spool in an accumulated strand of approximately 350,000 denier;

(b) assembling a number of such spools;

(c) leading a continuous strand from each spool simultaneously and separately through the nip of a first pair of heavy rollers;

(d) imparting a pressure to said nip sufiicient to provide a drag for a first stage of stretch;

(e) leading the continuous strands still separately to the nip of a second pair of similar heavy rollers;

(7) leading the same continuous strands separately through the nip of a third pair of similar heavy rollers;

(g) rotating the third pair of rollers at a higher speed then the second pair of rollers to provide a second stage stretch;

(h) rotating the second pair of rollers at a higher speed than the first pair of rollers to provide a first stage stretch;

(i) condensing the strands into a single stretched strand of approximately 1,200,000 denier; and

(j) winding the single stretched strand on a spool; all of the steps being carried out at room temperature and the total draw ratio employed being in the range of about 3.0-4.0.

5. The process of treating stretchable thermoplastic synthetic filaments to orient same molecularly comprising the steps of:

(a) combining continuous filaments of the thermoplastic material in-to several strands each of about 350,000 denier;

(b) passing the several strands at the same time and in fully separated condition between a pair of heavy smooth rolls to a second pair of rolls;

(c) applying pressure to the nip of the heavy rolls to provide a drag for first stage of stretch in each strand While still driving the rolls in a direction to feed the strands in a predetermined direction;

(d) stretching the strands which are still separated References Cited by the Examiner UNITED STATES PATENTS Killars 19-150 Abbott 19-150 Du-mont 264-290 Herele et a1. 264--290 Friederich 28-59.5 Mummery 264-290 ALEXANDER H. BRODMERKEL, Primary Examiner.

ALFRED L. LEAVITT, Examiner. 

1. THE PROCESS OF TREATING THERMOPLASTIC SYNTHETIC FILAMENTS COMPRISING THE STEPS OF: (A) WINDING APLURALITY OF ENDS OF SUBSTANTIALLY UNORIENTED FILAMENTS ON A SPOOL IN AN ACCUMMULATED STRAND HAVING A TOTAL DENIER IN THE RANGE OF ABOUT 50,000-1,00,000; (B) ASSEMBLING A NUMBER OF SUCH SPOOLS; (C) LEADING A CONTINUOS STRAND FROM EACH SPOOL SIMULTANEOUSLY AND SEPARATELY THROUGH THE NIP OF A FIRST PAIR OF HEAVY ROLLERS; (D) IMPARING A PRESSURE TO SAID NIP SUFFICIENT TO PROVIDE A DRAG FOR A FIRST STAGE OF STRETCH; (E) LEADING THE CONTINUOUS STRANDS SEPARATELY TO THE NIP OF A SECOND PAIR OF SIMILAR HEAVY ROLLERS; (F) LEADING THE CONTINUOUS STRANDS SEPARATELY THROUGH THE NIP OF A THIRD PAIF OF SIMILAR HEAVY ROLLERS; (G) ROTATING THETHIRD PAIR OF ROLLERS AT A HIGHER SPEED THEN THE SECOND PAIR OF ROLLERS TO PROVIDE A SECOND STAGE STRETCH; (H) ROTATING THE SECOND PAIR OF ROLLERS AT A HIGHER SPEED THAN THE FIRST PAIR OF ROLLERS TO PROVIDE A FIRST STAGE STRETCH; (I) CONDENSING THE STRANDS INTO A SINGLE STRETCHED STRAND; AND (J) WINDING THE SINGLE STRETCHED STRAND ON A SPOOL; ALL OF THE STEPS BEING CARRIED OUT AT A TEMPERATURE IN THE RANGE OF ABOU T20-35*C. AND THE TOTAL DRAW RATIO EMPLOYED BEING IN THE RANGE OF ABOUT 3.0-4.0. 